Synthesis and Characterisation of Organic Antimony and Bismuth Chains and Cycles Ioan Ghesner Dissertation submitted as a partial fulfillment of the requirements for the degree Doctor of Natural Science (Dr. rer. nat.) Faculty of Chemistry and Biology University of Bremen Bremen 2002 1. Referee: Prof. Dr. H. J. Breunig 2. Referee: Prof. Dr. G.-V. Röschenthaler Date of doctoral examination: 22. August 2002 Contents CONTENTS Introduction . 1 Aims of the present study . 4 Results and Discussion . 6 1. The trialkylantimony(V) dibromide R3SbBr2 [R = CH(SiMe3)2] and the trialkylantimony(V) hydroxy halide R3Sb(Br)OH (R = CH2SiMe3) . 6 1.1 Introduction . 6 1.2 Synthesis and characterisation of R3SbBr2 [R = CH(SiMe3)2] and of R3Sb(Br)OH (R = CH2SiMe3) . 6 2. Chiral organoantimony and -bismuth compounds, RR’SbCl, RR’BiCl, and RR’SbH; R = 2-(Me2NCH2)C6H4, R’ = CH(SiMe3)2. 13 2.1 Introduction . 13 2.2 Synthesis and characterisation of RR’SbCl, RR’BiCl, and RR’SbH; R = 2-(Me2NCH2)C6H4, R’ = CH(SiMe3)2 . 15 3. Organo antimony chain compounds, catena-R2Sb(SbR)nSbR2 . 22 3.1 Introduction . 22 3.2 Synthesis and characterisation of cyclo-[Cr(CO)4(R´2Sb-SbR-SbR-SbR´2)] (R´= Ph or Me, R = Me3SiCH2), cyclo-[Cr(CO)4(Ph2Sb-SbPh-SbR-SbPh2)], and cyclo-[Cr(CO)4(Me2Sb-SbR-SbR-SbMe2)W(CO)5] (R = Me3SiCH2) . 22 3.3 Synthesis and characterisation of the open-chain polystibanes, catena- t t Bu2Sb(SbCH3)nSb Bu2, catena-Mes2Sb(SbPh)nSbMes2 (n = 1, 2) and catena-R2Sb-(SbSiMe3)-SbR2 [R = 2-(Me2NCH2)C6H4]. Molecular and crystal structures of [(CO)5Cr(Me2Sb-SbMe2)Cr(CO)5] . 31 4. Bis(diorganobismuth)chalcogenides, (R2Bi)2E [E = S, Te; R = CH(SiMe3)2] . 39 4.1 Introduction . 39 Contents 4.2 Synthesis and characterisation of {[(Me3Si)2CH]2Bi}2S and {[(Me3Si)2CH]2Bi}2Te . 39 5. Transition metal complexes with cyclo-(RSbX)n [X = S, Se; R = CH(SiMe3)2] ligands . 44 5.1 Introduction . 44 5.2 Synthesis and characterisation of cyclo-(RSbX)2[W(CO)5]2 [X = S, Se; R = CH(SiMe3)2] . 44 6. Experimental section . 51 6.1 General comments . 51 6.2 Organoantimony- and bismuth halides . 53 Tris[bis(trimethylsilyl)methyl]antimony, [(Me3Si)2CH]3Sb . 53 Tris[bis(trimethylsilyl)methyl]antimony dibromide, [(Me3Si)2CH]3SbBr2 . 53 Tris[(trimethylsilyl)methyl]antimony bromide hydroxide, (Me3SiCH2)3Sb(OH)Br . 54 Chloro[2-(dimethylaminomethyl)phenyl]-[bis(trimethylsilyl)methyl]- stibine, [(2-Me2NCH2)C6H4][(Me3Si)2CH]SbCl . 55 Chloro[2-(dimethylaminomethyl)phenyl]-[bis(trimethylsilyl)methyl]- bismuthine, [(2-Me2NCH2)C6H4][(Me3Si)2CH]BiCl . 56 [2-(dimethylaminomethyl)phenyl]-[bis(trimethylsilyl)methyl]stiban, [(2-Me2NCH2)C6H4][(Me3Si)2CH]SbH . 56 6.3 Organoantimony chains . 58 Reactions of cyclo-(Me3SiCH2Sb)n (n = 4, 5) with distibanes . 58 Cyclo-[Cr(CO)4(Me2Sb-SbR-SbR-SbMe2)] (R = Me3SiCH2) . 59 Cyclo-[Cr(CO)4(Ph2Sb-SbR-SbR-SbPh2)] and Cyclo-[Cr(CO)4(Ph2Sb-SbPh-SbR-SbPh2)] (R = Me3SiCH2) . 60 Cyclo-[Cr(CO)4(Me2Sb-SbR-SbR-SbMe2)W(CO)5] (R = Me3SiCH2) . 61 Reaction of CH3SbCl2 and R2SbBr (R = Me3SiCH2)with Mg . 62 Contents t t Catena- Bu2Sb(SbCH3)nSb Bu2 (n = 1, 2) . 63 Catena-Mes2Sb(SbPh)nSbMes2 (n = 1, 2) . 64 Catena-R2Sb-(SbSiMe3)-SbR2 [R = 2-(Me2NCH2)C6H4] . 64 6.4 Bis(diorganobismuth) chalcogenides . 65 Bis[bis(bis(trimethylsilyl)methyl)bismuth]sulfide, {[(Me3Si)2CH]2Bi}2S . 65 Bis[bis(bis(trimethylsilyl)methyl)bismuth]telluride, {[(Me3Si)2CH]2Bi}2Te . 66 6.5 Transition metal complexes with cyclo-(RSbE)n ligands . 66 Cyclo-(RSbS)2[W(CO)5]2 [R = CH(SiMe3)2] . 66 Cyclo-(RSbSe)2[W(CO)5]2 [R = CH(SiMe3)2] . 67 7. Summary . 68 8. References . 73 9. Appendix . 81 9.1 Abbreviations . 81 9.2 Details of crystal structure determination . 83 CURRICULUM VITAE . 110 Publications . 111 Contributions to professional reports . 113 Acknowledgements . 114 Introduction Introduction The chemistry of organic antimony and bismuth compounds has expanded during the last decades, as illustrated by numerous recent reviews.[1-18] Considerable attention has been directed towards the synthesis and structure of novel compounds containing bonds between antimony or bismuth and group13-16 elements. Several research groups have focused on the preparation of compounds containing bonds between group 13 elements and the higher homologues of group 15, Sb and Bi. Research in this field was dedicated to the investigation of the E-X bond (X = gr. 13 element, E = Sb, Bi) and of the potential use of these compounds as precursors for semiconductors. An important result is the isolation by Schulz of the first complexes [19] with dibismuthane donor ligands and group 13 acceptors (A). Et tBu E 3 Et Bi Bi (A) Et EtBu Et 3 E = Al, Ga Among group 14-15 compounds those containing localised E=C (E = Sb, Bi) bonds have attracted considerable attention. Three examples of compounds containing localised Sb=C bonds in the solid state[20,21] have been described by Jones (B) but no reports of any stibaalkyne or bismaalkyne, or systems containing localised Bi=C bonds have been made. R Me3SiO C R Sb R Sb Sb (B) COSiMe3 O O H R t t t R = C6H2 Bu3-2,4,6 R = C6H2 Bu3-2,4,6 or C6H2 Bu3-2,4,6 1 Introduction Noteworthy results reported by Okazaki, Tokitoh and Power in the field of compounds containing bonds between group 15 elements are the synthesis and isolation of the first distibene, RSb=SbR[22], dibismuthene, RBi=BiR[23], stibabismuthene, RSb=BiR[24], and phosphabismuthene, RP=BiR[25]. However, doubly-bonded systems such as As=Sb or As=Bi remain unknown. Compounds with single Sb-Sb or Bi-Bi bonds such as cyclo-stibanes, cyclo-(RSb)n (n = 3 - 6), cyclo- bismuthanes, cyclo-(RBi)n (n = 3, 4), distibanes, R2Sb-SbR2, and dibismuthanes, [5,6] R2Bi-BiR2, are known mainly due to the work of Breunig. As far as catena- stibanes are concerned well-defined examples are rare and the isolation of oligomers of the type catena-R2Sb(SbR)nSbR2 (n = 1, 2) has not yet been achieved. The existence of catena-tri- and tetrastibanes in ring-chain equilibria is however well established.[26] On the other hand, extensive studies on the synthesis and structural characterisation of well defined catena-phosphanes of the type catena-R2P(PR)nPR2 (n = 1, 2) [27, 28] have led in the last decade to the X-ray structure determination of several catena-tri-[29, 30] and tetraphosphanes[31] (C). R R R R R R P R P P (C) P P P P R R R R Also, complexes with organophosphorus and -arsenic chains have been reported.[32-40] The free catena-phosphanes have been found to be unstable at room temperature whereas their coordination to transition metal fragments results in the formation of stable complexes. Either electrostatic or π-antibonding interactions of the P lone pairs in free catena-phosphanes are believed to destabilise the systems.[41] Studies on organoantimony and -bismuth chalcogenides were dedicated mainly to cyclic, cyclo-(RSbX)n, cyclo-(RBiX)n, cyclo-RnSbnXm, and chain, R2Sb-X-SbR2, R2Bi-X-BiR2, compounds (X = gr.16 element). X-ray diffraction studies on cyclo- (RSbX)n compounds are limited to the works of Okazaki and Breunig who reported [22] the crystal structures of two oxides, cyclo-(RSbO)2 [R = 2,4,6-[(Me3Si)2CH]3C6H2] [42] and cyclo-(RSbO)4 [R= CH(SiMe3)2] . No cyclo-(RBiX)n compounds were 2 Introduction structurally characterised. Possible intermediates by the synthesis of cyclo-(REX)n (E = Sb, Bi; X = gr.16 element) are the double-bond compounds RE=X. Low coordinated double-bond compounds between group 15 and group 16 elements, dithioxo-phosphorane [RP(S)=S][43] and diselenoxo-phosphorane [RP(Se)=Se][44], have been synthesised as stable compounds, and thioxophosphines [RP=S][45] and selenoxophosphines [RP=Se][46] stabilised by the coordination of an amino group have been observed in solution by NMR spectroscopy. As for the low coordinated double-bond compounds between antimony or bismuth and group 16 elements the number of works are limited to a recent paper of Okazaki, who reported on the trapping of antimony-sulfur double-bond, Sb=S, with nitrile oxides.[47] However, systems containing localised Sb=X or Bi=X (X = gr. 16 element) bonds still remain unknown. Although many of the trivalent antimony and bismuth compounds containing bonds to group 13-16 compounds have one or more unsymmetrically substituted antimony or bismuth atoms, making these molecules chiral, the configurational stability in such systems was not investigated due to their low thermal stability and to difficulties with their handling. Suitable candidates for atomic inversion studies on chiral antimony and bismuth centres are the more stable chiral triorganostibanes and -bismuthanes, RR’R’’E (E = Sb, Bi) and the chiral halostibanes and bismuthanes RR’EX (E = Sb, Bi; X = halogen atom). While inversion at N, P and As has been well documented for many years,[48] it is only recently that Akiba reported the first examples of inversion at [49,50] chiral antimony and bismuth centres. 3 Aims of the present study Aims of the present study Important synthons for the synthesis of organoantimony and -bismuth compounds with element-element bonds are the alkyl- and aryl-substituted antimony and bismuth halides. Antimony(V) compounds with the formula R3SbX2 where R may be either an alkyl or an aryl group and where X is a halogen or another electron attracting group are well known. No authentic R3Sb(OH)X compounds have been isolated in the solid state unless sterically demanding R and X groups are present.